RF Optimization (Drive Test)

Objective (brief)Understanding Optimization Overview H/w used in TEMSUsing TEMS Question in Interview Review

Objective Understanding meaning of RF Optimization H/w & S/W used in TEMSUnderstand GSM protocol Understand LAP-Dm Using TEMS Drop Call AnalysisHandover AnalysisTroubleshooting with TEMSQuestion in Interview Review

Understanding Optimization

Optimization is the process of improving operationof the network to better utilise available Infra.to provide customers of the service the best possiblequality of service.

H/w & S/W used in TEMS TEMS Dongle TEMS softwareLaptop GPSMobile

TMES Dongle

GPS

LatitudeLongitude

Latitude parallel to equator Longitude parallel to meridian

lat=19.187055Nlon=72.970878E

TEMS

Understand GSM protocol

Understand GSM protocol

Layer 3 Messages

Layer 3 Message System Information Type 1System Information Type 2System Information Type 3System Information Type 4System Information Type 5

SYSTEM INFORMATION TYPE 1

sent on the BCCH Information of control of the RACH

SYSTEM INFORMATION TYPE 2sent on the BCCH BCCH allocation in the neighbour cells.

SYSTEM INFORMATION TYPE 3The location area identification, The cell identityvarious other information about cell

System information type 5sent on the SACCH by the network

Any change in the neighbour cells description

Mobile station must analyse all correctly received messages.

PAGING REQUEST TYPE 1

sent on the CCCH by the network Up to two mobile stations

PAGING REQUEST TYPE 2

Three mobile stations

Understanding LAP-Dm

Layer 2 Messages

Using TEMS

Serving Cell

Cell ID16bit identifier

CGI = Cell ID + MCC + MNC +LAC

LAC < 65535(Cell Global Identity).

Base Station Identity Code

Important in border areas

3-bit network color code (NCC)assigned by regulatory authority

3-bit base-station color code (BCC)assigned by the network operator

Serving and Nighbouring cell

RxLEV

Measured in dBm unitsRxlev (-110 to 47) dbm RxLEV (0 to 63)GSM unit

Cell selectionFor example, If the minimum allowed level is -100dBm

Average received signal level is - 80dBm

The terminal evaluates C1 as +20.

The terminal always selects for attach the cell with highest C1.

Mobile allocation index offset (MAIO)

Time delay separating traffic channels.

Hopping sequence number (HSN).

The hopping pattern must be known both by the receiver and the transmitter.

The smallest amount of interference on a site

Frame Erasure RateSpeech Quality Index

Troubleshooting With TEMS

Troubleshooting With TEMS

Call drop

Hand Over

Congestion

Troubleshooting Call Drop

Check Interference Internal Co-channel Interference Change Frequency MS power Turn on Frequency Hopping Put more TRU Externalwireless alarm system Check Antenna Direction & Position Low Signal Strength Timing Advance Ping-pong Handover Call dropped on the TCH. Call dropped on the SDCCH DRAGON site

Excessive Timing advanceTA value is higher than TALIM

Reducing the coverageIf cell is really covering far away from BTSTilting the antennas, Reducing antenna heightChanging antenna Reducing output power

Excessive Timing advanceThe maximum BTS radius of 35 Km is divided into 64 TA steps

i.e. 1 TA = 547 Meter OR 550 Meter

Excessive Timing advance

Check the BTS error log Run commands: RXELP & RXMFP

Low signal strengthReceived signal level, Measured in dBm unitsRxlev (-110 to 47) dbm RxLEV (0 to 63)GSM unit.Either BCCH channel in idle modeboth BCCH and TCH

Handover Analysis

Handover AnalysisNo or few handover attempts:

whether the target cell is congested, if congested, solves the congestion problem.

Check if BTS is defined but might not be in service.

Handover Analysis

(BTS Log) PDF

Question in Interview 1 How to connect gps and mobile? GPS components used? whic mobiles are been used? Laptop which pin is used to connect the gps? what parameters are used to measure call drop? what parameters are used to measure handoff? what u mean by RX-LEVEL? what u mean by RX-QUAL? what does the term power budget mean?

Assignment for Student How can you calculate the coverage and capacity of a GSM network? How do you make a link budget? Which parameters are included in System Information? How can you increase coverage and capacity? How does the choice of antennas affect network performance? What are C/I, C/A ? How can repeaters improve the network performance?

Thank you

Design by Mahesh Tawade